Bag making machine



Feb. 27, 1934. B, D. GREENLAW BAG MAKING MACHINE e sn'eets-sheet 1 Filed Aug. 6, 1931 Feb. 27, 1934. B. D. GREENLAW 1,949,273

BAG MAKING MACHINE Filed Aug. 6, 1931 6 Sheets-Sheet 2 Feb. 27, 1934. B. D. GREENLAW y BAG MAKING MACHINE Filed Aug. 5, 1951 6 Sheets-Sheet 3 Feb. 27, 1934. B. D. GREENLAW 1,949,273

BAG MAKING MACHINE Filed Aug. 6, 1931 6 Sheets-Sheet 4 Feb- 27, 1934- B. D. GREENLAW Y 1,949,273

BAG MAKING MACHINE Filed Aug. 6, '1931 6 Sheets-Sheet 5 o3 n *i .w Q g o n '5 u i I :g u i im ||I I Hl| ||v Y m w; a N

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vla. D. GEl-:NLAW

BAG MAKING MACHINE Filed Aug. 6, 1951 6 Sheets-Sheet 6 lwuentoz.' urpee G'Jreemlcua GMM, K

Patented Feb. 27, 1934 UNITED `STATES PATENT ortica BAG MAKING MACHINE setts Application August 6, 1931. serial No. 555,620

31 Claims.

The invention relates to machines for making envelopes, and particularly to that type of envelope having a rip string. It is an aim of the invention to coordinate the string placing mechanism mechanically and functionally with certain paris of standard envelope machines permitting the elimination of other parts, with the result that simplification of the machine is attained.

Another purpose is to evolve a novel mechanism for feeding and placing the string. I am aware that mechanisms have been heretofore employed for laying strings in the folds of paper containers, but I depart from prior practices in a radical relb spect--in addition to evolving novel structural pars and combinations-by laying the string before the fold or crease is made, utilizing my string-placing means and the string as a crease former simultaneously with the making of a fold,

timing the tension and placing the string in a novel relation to the operation of the folding mechanism. In addition, the string is laid in a peculiar relation to the container to the end that it causes the folding of the paper stock in such manner that the string and the gum for securing it are kept out of communication with the contents of the container when in use. Also, the string is so arranged with respect to the container that the container will be severed cleanly at the same time that other new advantages of my invention are attained.

An important purpose of the invention is to present a novel gumming means for the string. Another important purpose is to evolve a novel means to prevent impairment of operation of the machine by accumulation of string when envelope blanks are not supplied. It is a specific object to present a novel mechanism for feeding, gripping, and positioning the string so that sim- 4o plicity may be attained, at the same time that the string is held with special high tension and utilized as indicated.

Additional objects, advantages and features of invention reside in the construction, arrangement and combination of parts involved in the embodiment of the invention, as will be understood from the following description and accompanying drawings, presenting one embodiment of the invention, alternative constructions being comprised within the scope of the claims as appended. In the drawings,

Figure l is a top View of the folding mechanism of the envelope machine, showing my string feed and placing devices in gum-applying position, the

5 fcarrier and other elements being removed` Figure 2 is a perspective view of the folding parts and string-holding means in position for the bottom fold.

Figure 3 is a front elevation of the machine with parts omitted.

Figure 4 is an enlarged detail front view of the travelling grip in string-receiving position.

Figure 5 is a similar view showing the travelling grip in gripping position.

Figure 6 is a front view showing the travelling grip in position to hold the string while gum is applied thereto, the gum-applying device being removed.

Figure 7 is a fragmentary detail top view of the right hand grip release cam.

Figure 8 is a rear elevation of the release means for the travelling gripper and automatic stop feed for the string laying and gumming mechanism.

Figure 9 is a fragmentary View showing the cutter and operating connections.

Figure l0 is a fragmentary sectional view of the string gummer.

Figure 11 is a detail longitudinal section ofthe travelling gripper.

There is illustrated a part of an envelope machine of well-known construction, having a frame 14 including the heavy table plate 15, on or over which the principal operative devices of my invention and the envelope forming means are mounted. An envelope platen 16 is shown upon which the blank is folded, and at respective sides of the platen the usual left and right folder wings 17 and 18 are pivotally mounted to be operated by the connecting yrods 19 from the customary sources. In this machine no top fold is made, and no crease is formed at the bottom preliminary to folding of the bottom, as will be described, the

latter crease being formed simultaneously with the folding operation, which is accomplished by a familiar form of bottom folder 20 (Fig. 2) cooperating with which is the presser 21, operated -in conjunction with the folder 20 as heretofore. The blank or other stock may be fed to the machine in the customary way, and one side flap and the bottom gurnmed as required incident to the style and order of folding, the gumming devices not being shown, as their construction will be well understood. The folder 20 is operated by a usual arm 20' and link 20a.

The folding wings and platen are replaceable by others to adapt the machine to different forms and sizes of envelopes, as will be understood, and my string-placing mechanism is adaptable to such changes Without modifying its function, as will appear.

The string used in this machine is preferably a good, strong thread shown carried on a spool 22 at the right hand side on the fran-ie 14` from which spool it is fed directly to the mechanism ofl my invention.

On a line parallel to the line of the bottom fold, and spaced therefrom toward the front of the machine a short distance a pair of bearing blocks 23 areV mounted on the table 15. In these there is revolubly mounted a rock shaft 24 havingy a spline groove 25 or other form of spline over its major part between the bearings named. At the extreme right hand end of this shaft and imme-` without changing the proportions of the driv-V ing connectionsl The connection of theV connectm ing rod `27 with the arm 28 however. Vis adjustable longitudinally of the arm. The arm 28 isalso'f' held yieldingly in initial position by a retractile spring 30. The eccentric 26 also has thereon front and rear stop screws 31.-32 to limit move# ment of the rock shaft 24 by striking the top of the table at respective limits of its rocking movement.

which the thread 34 passes from the spool. i

Immediately at the left of the right hand bearving 23 the shaft 24 has fixed thereon an initially upstanding thread carrying arm 35, the upper en'd of which is provided with a thread guide sleeve 36 parallel to the shaft 24,-and through the sleeve the thread is extended, the inner' end of this sleeve terminating at the left and lower side of a jaw 37 of a gripper 38. It projects toward the left and has an eye 38' at its extremity through which the thread finally passes at this part. A

movable jaw 39 is pivoted on the jaw 3'7 by YmeansY of an arm 40 (Fig. 2) which extends downward at the rear side of the lower jaw from the right hand end of the movable one, in suchwmanner that when the arm swings `toward the left the entire jaw 39 is lifted, leaving the space open thereunder from the front side, so that the thread may be laid therein readily. The arm 40 is connected to a plunger shaft 41 projecting through and splined in the arm 35 parallel to the shaft 24.

It has at its right hand end a wiper roller 42, inward of which a nut 43 is engaged on the plunger confining a spring 44 against aY bushing 45 in the arm 28 in which Vthe plunger 4l is fitted. 1

The spring thrusts the plunger toward the right, tending to close the jaw 39. The wiper 42 rotates on an axis radial to the shaft 24 and fixed on the adjacent bearing 23 adjustable longitudinally with respect to the shaft 24 there is a stati'nary cam block 46 having' a high part presented toward the left so as to'engage the wiper 42 when at elevated position holding the plunger toward the left and maintaining the gripper 38 open. It slopes away toward the right on the rear part so that upon Vrockingrof the shaft 24 to swing the arm 35 toward the rear the plunger will be quickly freed for movement to the right and closing of the gripper 38. The gripper will thus remain closed upon the string throughout movement to its rear limit, and until it returns Vto initial position.

On the eccentric also there is a threadr Yguide and friction thread tension 33 vthrough Upon the shaft 274 and reciprocable between the gripper 38 and the left hand bearing 23 there is a splined sleeve 47 upon which is held a revoluble external collar 48. Pivoted upon this collar there is a connecting rod .49 operated by a lever 50 at the left side of the machine, which lever may be moved by usual connections for such members familiar in this type of machine. The sleeve 47 has fixed thereon an arm 51 similar to he arm 33, the upper end of which is formed with a collet sleeve 52 coaxial with the sleeve 36 forming Vthe mounting of a travelling gripper 53. The `sleeve is formed with a small bore at the left end receiving slidably the stem portion 54 of a sliding jaw 55, the right hand end of the bore being enlarged to accommodate the jaw from a point medially of the sleeveand being flared at the mouth of the bore. Pivoted on the jaw 55 there is a jaw 56 and between the two a spring 57 is confined tending to open the jaws. The jaws are symmetrically formed. being enlarged as at 58 near their forward ends, this enlargement' being circular and of larger diameter than the larger bore in the sleeve, and being tapered rearwardly so that when the jaws are drawn toward the left theyl will wedge in the mouth of the bore, and be compressed together. When so wedged, the larger parts of the jaws 55 and 56 stop short of the smaller bore in the left end of the sleeve'52. The stem 54 projects a distance from the left end of the sleeve where a longitudinally adjustable collar 58 is threaded on thestem and secured'by a lock nut 59. In the outer or left end of this collar in turn there is an adjustable head 60 inthe form ofV a screw engaged in the end of the collar 58 outward and to the left of the stem 54. Between the 'nut 59`and the sleeve 54 a helical spring 61 is confined,'tending to draw the jaws and close them. A bracket 62 is provided on the left-side of the arm 51 projecting longitudinally of the stem 54 and spaced suitably below this stem. On the bracket a detent vor pawl 63 is pvoted,rhaving a left end formed with a bill 64 adapted to engage the extremity of the collar whenthe latter is pressed to the Vright'against the action of the springrl, so as to hold thejawsin open position.' The detent is spring pressed'so that it tends to move to and remain in such engaged position. The detent has an arm 65 extended to the left provided with a linger 66 projected toward the front which may be pressed downwardly to releaseethe detent. In order to operate this finger a trip device is provided at a position to engage and' depress the finger when the travelling gripper reaches the right hand llimit of its travel from the left. 'The fingerv is formed with a knife edge at the right hand side from which the top face slopes upwardly toward the left, and the trip device includes a lever or arm 67 pivoted on a post 68 fixed on the table 15. A finger 69 projects rearwardly from the lever into the path which the finger 66 travels forward. The rear edge of the finger 69 has a knife edge at the left side at a slight-ly higher level than the knife edge of the' finger 66 and the underside of -the finger 59 is adapted Yto ride upon the slopingside of the finger 66 and depress the same, means 'being provided to hold the lever against yielding to the upward pressure,l as will be described. Either or both fingers are of a width in the direction of travel of the gripper such that the release of the'detent 63 occurs without the fingers passing out of engagement, and before forward movement of the gripper to. gripping posi- -tion ceases. The finger 66 can then back ofi 'the ringer 69 easily when the gripper 53 moves to the left again.

The head 60 lies close to the table 15 when in string-placing position, and at the left of such position of the head there is mounted on thetable top a guide sleeve 70 in which a gripper and reset release plunger or bolt 71 is slidable in line with the head 60 when the latter is lowered, a wiper roller 72 being mounted in the right hand end of the bolt. This bolt is operated by a connecting rod 73 from an oscillating arm 74 connected suitably with the drive of the envelope machine. The bolt is operated to release the travelling gripper 53 immediately before the arms 35 and 51 are raised.

At one side of the platen 16 there is mounted a stationary upstanding cutter blade 75 (Figs. 2 and 9), while pivoted beside it there is a movable shear blade 76 rearwardly of the first blade arranged to swing forwardly to cut a string when held between the two. The pivoted blade has an arm 77 extending downwardly through suitable slots in the table plate 15. The cutter 76 is operated by a reciprocating rod 78 mounted slidably on the under side of the table 15 and connected to the arm 77. At its outer end this rod is connected to an arm 79 adjustably secured on a rock shaft 80 mounted in suitable bearings on the under side of the table 15 near its front edge, and rocked by any suitable connection with the driving mechanism of the envelope machine, not shown.

The gumming of the string may be variously accomplished but in the present instance there is illustrated a stationary trough or box 81 mounted over the bottom folder (Fig. 1). In this there is revolubly mounted a roll 82 extending throughout the length of the trough, its shaft projecting at one end and having suitable operative connections 83. Under the track customarily provided for the carrier of the blanks in the regular machine, there are two bearings 84 in which parallel rods 85 are slidable carrying revolubly mountedon their inner or rear ends a gumming roller 86, the length of which is slightly less than the width of the envelope to be made. The roller is in line with and parallel to the-bottom fold of the envelope. The forward ends of the .rods are connected by a cross head 87 spaced a distancel from the bearings 84 and helical springs 88 are engaged around the intervening portions of the rods conned against the bearings by collars 89 adjustable on the rods. By this means the roller 86 is yieldingly held at the outer limit of its movement toward the front of the machine and in contact with the roll 82 at the upper portion of the latter. The bearings 84 may be incorporated on the'box 81 so that the complete gumming device and box may be removed as a unit. In the box there is shown a wiper pla'e 90 by which the amount of gum carried over the roll is regulated. In the regular machine the carrier above mentioned is operated by means of a lever arm 91 extending upwardly at the front of the machine and'movng forwardly and rearwardly. The arm has pivoted at its upper end a link 92 branched' rearwardly and having a cross bar 93 engaged with the extremities of the link. This bar is connected to the carrier 94, which is broken away or omitted in the views, comprising no novel part of the present invention and not being essential to an understanding thereof.

Engaged through ihe cross head 87 there is a screw 95, secured by a lock nut 98, the head of the screw being broad and located at the front side of the cross head in line with the shaft 93, so that the latter will engage the screw and move the crosshead wih the rods 85 and roller 86 inwardly to gum-applying relation to the spring 34, as shown in Figure l0.

In the operation of the machine, the shaft 93 engages the screw 95 after the carrier has been moved inward a distance, at which time the string 34 is in position just after the travelling gripper has drawn. it to the left fully, and before the shaft 24 is rocked to swing the string down.

The arm or lever 67 is controlled in such manner that in case the paper feeding means or operator fails to supply paper to the machine, the string will not be drawn, and laid over the platen. This is accomplished by arranging the lever or arm 67to be shifted so as not to release the Ydetent 63 when there is no paper in the machine, and consequently the travelling gripper will not close on the string and draw it to gumming position, nor lay it on the envelope. The lever 67 is supported by a cam lever 97 pivoted on a bracket 98 a distance above the lever 67 so as to swing in the same plane, and having a depending part apertured at 99 to receive the extremity of the lever 67 therethrough. This last named extremity has an upwardly inclined face 101, and the lever 97 is provided with a wiper 100 resting upon this inclined face. When the depending lever is' at the right hand limit of its movement (Fig. 8) the nger lever 67 is at its uppermost position and its finger 69 in position to wipe the finger 66 as the latter moves forward (to the right in Fig. l; to the left in Fig. 8). When the depending lever is moving to the left, however, it bears throughout upon the inclined part 101 of the lever 67 and moves it downwardly, displacing the finger 69 below the finger 66 so that the latter moves freely past and the travelling gripper remains open instead of closing upon the string. A spring 102 may be utilized to support the lever 67 yieldingly.

'Ihe lever 97 is pivoted on a bracket 98 on top of the post 68, and has an upwardly extending armature arm`105 above its pivot in operative relation to an electro-magnet 106 which is in an open circuit 109 terminating at one end at an insulated contact plug 107 xed in the regular plunger plate 108 of the envelope machine, the other end of the circuit being merely grounded on the machine frame or other proper part, as indicated diagrammatically in Figure 3. The circuit is shown as including a source of current 110.

The contact is mounted by boring a suitable sized opening through the plate 108 and setting the plug therein with ouick detachable connection 111. Thus plug may be of any approved construction including a case part to fit the opening in the plate 108, lso that it may be readily removed and mounted on other plunger plates when a change of size of envelope is involved. The plug includes a yieldingly mounted contact 112 which projects below the-plate 108 except when the latter presses on the work or platen 16. this account if no paper is in the machine. the Contact engages the metal of the platen and closes the circuit to the magnet causing operation of the lever 97 and preventing a piece of string from being dropped into the machine. On the other hand, if there is paper properly fed to the machine the blank under the plunger insulates the plug from the platen and leaves the circuit to the magnet open, and the mechanism free to operate normally.

The parts being in the position shown in Figure 2, the gripper 39 will be open, and the thread may be manually adjusted in the friction device 33 and inserted through the guide sleeve 36. The end is then drawn through the last mentioned sleeve, swung laterally under the jaw 39 and its extremity inserted through the eye 38 allowing the end to project about three-eighths of an inch, and adjusted so that it will extend rectilinearly from the eye.

In the operation of this machine, a folding box is employed into which a paper blank is pressed by a plunger by which the creases for the side flaps are formed, no crease being formed at the bottom or'across the top, but the end flaps'left flat. After the creasing operation the wings 17 and 18 are operated in succession toV fold and press the sideraps. While the creasing operation is occurring, the travelling gripper 54 with jaws open and detent 63 engaged moves to the right, lthe endof the string projecting from the right gripper iri position to enterthe jaws of the travelling gripper.v As the'traveller 53 reaches this position, the finger 66 of the detent63 having ridden upon the cam part 69 of the lever 6'7 `is depressed sufliciently for the bill 64 to clear the end of the collar 58, permitting the spring 61 to shoot the stem 54 to the left, and drawing the jaws-55 and 56 into the collet sleeve 52, whereby the jaws of the travelling gripper are closed on the string. It is apparent that if there is no blank in the folding box, the contact 112 engages the platen 16, closing the circuit through the magposition, extending the string 34 before the gumrning roller 86 which is next operated. Thebottom folden-begins its forward movement at this stage, and the shaft 23 is operated, placing and holding the string taut while the bottom fold is completed.

The cutter 76 now operates and at the same time the plunger 72 moves to the right, releasing the travelling gripper and resetting the same in open position. The shaft 23 now rocks back to initial position, while the connecting rod moves the sleeve toward the right. Ejection of the completed envelope by the usual medium is now effected and the carrier begins movement of a new blank over the folding box. During this 'movement the traveller grips the string by operation of the trip as previously described, and quickly drawsthe string to gumming position before the last part Vof the movement ofthe carrier occurs. In this movement of the carrier the screw 95 is engaged and the Ygummer roll operated as stated.

1; In an envelope machine, a platen, flap folders for respective flaps of a blank, and means to hold the blank while the flaps are folded includng a string holding device adapted to hold a string taut therein, constructed and operative to move the string into pressing work-holding engagement with the blank at the line of fold, during operation of the respective folder, means to move the string holding means into and out of operative position relative to the fold, and means to operate the folder while the string is in taut pressing engagement With the blank.

2. In a machine of the character described. a blank supporting a platen, means to crease the blank at two sides and to hold the blank upon the platen, side folders for the side naps of the blank, a bottom folder a string supply means to move and hold a part vof the string taut upon the exterior end portion of the folded side flaps during operation of the bottom folder, where- ,by the string holds the work and forms they crease at this part, and means to cut the string.

3. In a machine of the character described, a

Ablank supporting platen, means to crease two flaps of a blank and hold the blank upon the platen, folders for the said two flaps of the string, and means to cut the string after the operation of the end folder.

4. An envelope machine comprising an envelope forming mechanism, including a bottom envelope blank flap holder, a string supply laterally thereadjacent, arotary shaft mounted on a fixed axis parallel to and adjacent the line of bottom fold, an arm on Vthe shaft having a string grip movable therewith on a radius including the line of the Ybottom fold, a travelling gripper splined on the shaft, means to move the gripper from adjacent the string grip to position'spaced therefrom a distance exceeding the width ofthe envelope, means to operate the gripper to grip a string projected from said string grip, means to rock said shaft in coordination with the folder to lay an engaged string upon'an envelope immediately before operation of said folder, means to sever the string and means to release said grip and gripper alternately. Y

5. The structure of claim 4 in Whichsaid grip comprises a stationary'jaw havingV an eye at the extremity for passage of a string, a pivoted jaw on the first jaw movable to clamp a.

string upon the rst jaw, a spring pressed operating member movably mounted on the said arm and connected with the pivoted jaw, 'and a stationary cam positioned to engage the operating member when the said arm is in initial position, to hold'the grip open, whereby when the grip is moved toward the envelope, the cam clears the operating member andvpermits the grip to close. Y e Y v I 6`. The structure of vclaim 4 in which said grip comprises a stationary jaw having an eye at the extremity for passage of a string, a pivoted jaw on the first jaw movable to clamp a string upon the first-jaw, a spring pressed operating member movably mounted on the said arm and connected with the pivoted jaw, and a stationary cam positioned to engage the operating member when said varm is in initial position, to hold the grip open, whereby when the grip is .moved toing member and permits the grip lto close, and a string friction device on the grip between the source and said grip.

'7. A structure as in claim 4 in which the travward the envelope, the' cam clears the Vopera/tist@ in line with said fold and means to operate the plunger to engage the head to release the jaws in succession with the operation of the said means to sever the string, means to hold the travelling gripper open, and means to release the gripper for closing coincidently with movement into close proximity with the rst named grip.

8. A structure as in claim 4 in which the travelling gripper comprises a collet sleeve, having slidable mounting on the shaft and spaced therefrom, a pair of spring-opened jaws having tapered parts adapted to wedge in the collet to closef' the jaws, a stem extending from the jaws through the collet and having a head outwardly of the collet opposite the jaws, a spring coniined between the head and collet, a plunger mounted on the machine spaced from the shaft in line with said fold and means to operate the plunger to engage the head to release the jaws in succession with the operation of the, said means to sever the string, means to hold the travelling gripper open, and means to release the gripper for closing coincidently with movement into close proximity with the rst named grip, said means to hold the travelling gripper open consisting of a springpressed latch mounted on the travelling gripper and a stationary release beside the path of the gripper, arranged to engage and release the latch under movement of the travelling gripper to operative relation to said grip.

9. A structure as in claim 4 in which the travelling gripper comprises a collet sleeve, having slidable mounting on the shaft and spaced therefrom, a pair of spring-opened jaws having tapered parts adapted to wedge in the collet to close the jaws, a stem extended from the jaws through the collet and having a head outwardly of the collet opposite the jaws, a spring conwned between the head and collet, a plunger mounted on the machine spaced from the shaft in line with said fold and means to operate the plunger to engage the head to release the jaws in succession with the operation of the said means to sever the string, means to hold the travelling gripper open, and means to release the gripper for closing coincidently with movement into close proximity with the iirst named grip, said means to hold the travelling gripper open consisting of a springpressed latch mounted on the travelling gripper and a stationary release beside the path of the gripper, arranged to engage and release the latch under movement of the travelling gripper to operative relation to'sad grip.

10. In an envelope machine, the combination of a platen, a blank feeding and folding device, means to grip and hold a string under tension movable with the string into position with the string laid upon the work, whereby to clamp the Work while being folded, means to operate the folding device while said string is so held, means to cut the string thereafter, and means to release the string grips after operation of the cutter.

11. The structure of claim 4 and means to apply adhesive to the string when the travelling gripper draws toits limit from the stationary grip.

12. The structure of claim 4 in which a gum applying device is incorporated having gumming members movable into line between the stationary and travelling grips when the latter is at the limit of movement from-the rst grip.

13. 'I'he structure of claim 4 in which a gumming device is provided, including gumming rolls movable into the path of the string in the grip and gripper, means to move the rolls into such position and return after movement of the travelling gripper to string stretching position, and means to supply adhesive to the rolls.

14. A string gripper and placer comprising a.

string supply, a revolubly mounted shaft, a string holder device xed at one end thereof, a travellng string holder slidably splined on the shaft means to reciprocate the traveller, said traveller having a string grip, means to operate the grip to engage string projected from the string holder, means to rock the shaft to swig the string while taut upon an envelope, at a line of fold, means to sever the string and means to release the holder and grip.

l5. The structure of claim 14 including a string gummingmeans positioned and operatively connected therewith to apply gum to string between the holder' and grip.

1S, ln a rip string container making machine, a platen, means to hold a blank thereover, a string supply including a string-end holder, a travelling gripper movable to grip the string at the end holder and to draw the string therefrom, and means to move and place the string, means to normally release the gripper, and separate means to control the gripper including means responsive to a blank in folding position to oppose operation of the separate control means.

17. The structure of claim 16 in which the separate` control mean's comprises a member tending 'to operate the release arranged and movable to engage a blank yieldingly when in operative position, and be held by the blank in inoperative position.

18. The structure of claim 16 in which the separate control means consists of a magnetic gripper release, including an electromagnet operative to actuate the release, one contact below the operative position of the blank, one contact movable with machine parts downwardly upon the rst contact on each blank-spacing operation of the machine, and an energizing circuit to the magnet through said contacts.

-19. The structure of claim 16 including a string gumming device operative movable to engage the string when initially drawn to operative length.

20. The structure of claim 16 in which the gripper is spring operated tending to close, a detent device to hold the gripper open, means to release the detent at gripping position.

2l. In c. rip string container making machine, a platen, means to hold a blank thereover, a string supply including a string-end holder. e. travelling gripper movable to grip the string at the end holder and to draw the string therefrom, means to move and place the string, means to normally operate the gripper, and separate means to control the gripper including means responsive to a blank in folding positionto oppose operation of the separate control means.

22. The structure of claim 21 in which the vseparate control means comprises a member tending to operate the release, arranged and movable to yieldingly engage a blank when in operative position and be held by the blank in inoperative position.

23. The structure of claim 21 in which the separate control means consists of a magnetic gripper release, including an electro-magnet operative to actuate the release, one contact below the operative position of the blank, one Contact movable with machine parts downwardly upon' the rst Contact on each blank-placing operation of the machine, an energizing circuit to the magnet through said contacts.

25. The structure of claim 21 in which the gripper is spring-operated tending to close, a detent to, hold the gripper open, said means to normally operate the gripper, being operative to release the detent when the gripper is in receiving relation to the string, and being movable out of detez'it releasing position, saidseparate control means being operative and tending to move the detent release to inoperative position. I

26. In an envelope machine, the combination of a metal platen element, a creasing plunger, folding means, a string gumming and placing means,

` stop means for the string placing means including a member operative to hold the stop inV inoperative position in response to a blank interposed between the plunger and platen.

2'7. In an envelope machine, the combination of Va' metal platen element, a creasing plunger, folding means, `a string gumming and placing means, stop means for the string placing means including an electrical device adapted to` operate the stop when energized, an electrical source, and open circuit connections between the electrical device, the plunger, the platen, and electrical source, constructed to be closed by coen'gagement of the plunger and platen, and in a relation to be insulated by an interposed blank.

28. In a'machine of the character described a blank folding mechanism consisting of a platen, means to initially hold a blank thereon, two side folders, a string supply, means to draw the string and hold it taut across theblank on thepla'ten transverse to the side folds, means operative while the string holding means holds the string taut on the work to fold a part of the blank over the string and secure it, and means to cut the string.

29.` In a machine of the character described, a blank folding mechanism consisting of a platen,

means to initially hold'a blank thereon two sidel folders, a stringA supply, a travelling gripper movable toward and away from the string supply,

means to grip the string next the supply when drawn to a length, means to move the grippers to position with the string across the blank transverse to the line of side fold, and means to fold the adjacent ilap of such envelope while said 8O grippers are operative to holdthe string whereby the string serves as a crea-ser and holder for the blank.

30. In a machine of the character described, a

platen, a plunger, a string supply, a travelling gripper having spring-,operated jaws, a 'detentto hold the device open against the tension of the operatingspring, said detent having an inclined strike member, a stationary support, a trip movably mounted thereon including a member normally projected into the path of said strike to engage and cause displacement of vthe detenty as the travelling grip reaches string-gripping position, yielding means to hold the trip means in norm'al position. an electro-magnet having a 95 movable armature connected to the trip operative by the magnet to move the trip to inoperative relation to said strike, and a circuit including a make and break device, the platen being oneV and the plunger another switch element therein.

31'. In an envelope machine of 'the character described, an envelopeblank folding mechanism, including an operating member'for a part thereof reciprocable to and from operative position, a string feed comprising means to 'drawa string 105 taut Yinto initial position parallel to one line of fold of the blank and spaced therefrom, and to swing-.the string upon the envelope blank in cooperative relation w th the folding mechanism,a gumming device including a gumming roll, means 11() to coatthe roll with adhesive and means to move tno roll into engagement Vwitlrtlrie string while taut in said initialposition and back to coating position spaced from the string including a member interposed in the path of the said operating member near the terminal part of movement of the latter, and yielding means engaged with the roll to return and hold it to coating-position.

BURPEE-D. GREENLAW.

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